In recent years, as a display device for alternative use of a liquid crystal display device, an organic electroluminescent display device (organic EL display device) using organic electroluminescent elements (organic EL elements) are receiving attention. The organic EL display device is of a self-luminous type, and has characteristics of low power consumption. It is also considered as having the response characteristic of a sufficient level also with respect to a high-speed video signal with high definition, and thus is under active development for practical use thereof.
The organic EL element generally has the lamination configuration in which a first electrode, an organic layer, and a second electrode are disposed one on the other. The organic layer includes a light-emitting layer made of an organic light-emitting material. With such an organic EL element, an attempt has been made to control light to be generated in the light-emitting layer by configuring the organic EL element like a resonator, i.e., by seeking to find the optimal thickness of each of the layers configuring the organic layer (as an example, refer to the brochure of WO 01/39554). Controlling the light as such includes improving the purity of color of light emission, increasing the efficiency of light emission, and others.
With the configuration of a resonator used as such, however, there may be a possibility of causing a problem to the viewing angle dependence of the chromaticity and luminance, that is, with a larger viewing angle, causing a problem of largely shifting the peak wavelength in the spectrum of a light coming from the organic EL display device, or greatly reducing the intensity of light, for example. In consideration thereof, keeping the level of resonance as low as possible is preferable, that is, making the organic layer as thin as possible is preferable (refer to WO 01/39554 pamphlet described above). However, with the organic layer reduced in thickness, as schematically shown in FIG. 13, if there is any particle (foreign substance) or protrusion on the first electrode, it means that the resulting organic layer does not provide the perfect coverage, thereby possibly causing a short circuit between the first and second electrodes. If such a short circuit occurs, in an active-matrix organic EL display device, any pixel in which such a short circuit is occurring becomes deficient, thereby deteriorating the display quality of the organic EL display device. Also in a passive-matrix organic EL display device, caused is the shortage of lines, and this also deteriorates the display quality of the organic EL display device. Such a problem becomes more apparent when the organic EL display device is large in size. This is because the viewing angle characteristics are expected to be much better but the allowed number of deficits per unit area is reduced.
So far, various attempts have been made to reduce the possibility of causing a short circuit between the first and second electrodes. As an example, Japanese Unexamined Patent Publication No. 2001-035667 describes a technology of providing by insertion a high-resistance layer between an anode electrode and an organic film in an organic EL display device of a bottom emission type. As another example, Japanese Unexamined Patent Publication No. 2006-338916 describes a technology of, in an organic EL display device of a top emission type, configuring an anode electrode to have two layers, and increasing the resistance of one of the layers of the anode electrode closer to an organic layer. As still another example, Japanese Unexamined Patent Publication No. 2005-209647 describes a technology of, in an organic EL display device of a bottom emission type, configuring a cathode electrode to have two layers, and increasing the resistance of one of the layers of the anode electrode closer to an organic layer.